Diffusion pumps



Feb. 2, 1960 TAMOTSU SONE DIFFUSION PUMPS Filed Oct. 25, 1957 5 Sheets-Sheet 1 1N VENTOR ATTORNEYS Feb. 2 1960 TAMOTSU SONE DIFFUSION PUMPS 5 Sheets-Sheet 2 Filed Oct. 25, 1957 INVENTOR mm mw ATTORNEYS Feb. 2, 1960 TAMOTSU SONE DIFFUSION PUMPS 5 Sheets-Sheet 3 Filed Oct. 25, 1957 INVENTOR 7m jm ATTORNEYS United States Pa n 2,923,458 DIFFUSION PUMPS Tamotsu Sone, Tokyo, Japan 7 Application October 25, 1957, Serial No. 692,290

Claims priority, application Japan November 1, 1956 6 Claims. (Cl. 230-101) This invention relates to improvements in'difiusion pumps.

Heretofore, an oil diffusion pump, functionates in "such a manner that oil vapor after ejected from'a nozzle throat forms a high speed stream and the circumferential portion of the stream carries away gas molecules into a chamber beyond the nozzle. The central portionof the vapor stream proceeds forward without contributing for the aspiration of gas. 1

An evacuating system ofja moderately high vacuum class generally consists of a high vacuum diffusion, a booster diffusion, and a backing mechanical pump. The necessity of-the booster diifusion pump is caused'by the ineffectiveness of the high vacuum diffusion pump for a backing pressure produced by the mechanical pump. If the'h'igh vacuum diifusion pump is sufliciently je'ifective for higher' backing pressure as mentioned, the 'bo'oster" pump would be omissible.

In the conventional structure,only one tube is provided for one nozzle throat to function'ate as a pump, said "tube being made, in addition, to actuate as a'condenser foroil vapor. It has been considered, in general, that, in 'order to aspirate gas contained in a single chamber through a number of aspirating tubes,'it is necessary to use as many number of nozzle throats as the aspirating tubes.

'Meantime, it is required that oil vaporization'should be effected as much as possible in quantity out of the whole quantity of oil as small amount as possible at a temperature as low as possible order to 'keep the'thermal decomposition of the oil as little as possible.

*One-Objcct of this inventibnis 'toprovide an oildiifusion pump capable of speeding up anevacuating'operation.

Another object of this invention is to "provide an oil diffusion pump whereby a'booster'pump is not necessary i'n'a moderately high vacuum evacuating system.

Still another object of this invention is 'to provide an oil diffusion pump mechanically rigid enough against a vacuum condition.

Further another object of this invention is to provide an oil diffusion pump wherein'the evaporation of oil takes place quite smoothly. V i g A still further object of this inventionist'o provide 'an oil diffusion pump which may be set somewhat inclined.

Briefly stated in accordance'with one'aspect'of this invention, there is provided an'oil'ditfusion pump comprising a boiler and a cylindricalbody which is divided into-a high vac uum chamber and a low vacuum chamber and comprises an inner assembly andanin'takeline; said inner assembly being arranged c'once'ntrically'with said body and comprising a nozzle: through which a streamof vapour of said oil is made to flow,the1peripheral'portion of said stream drawing gas molecules within'said high vacuum chamber, and said drawn gas molecules being carried by the central portion of said stream into said low vacuum-chamber. I

The-invention will be'better understood and other objects' and additional advantages of the-invention will became apparent ripen perusal of thefollowing description ice taken in connection with the drawings, and the scope .of the invention will be defined in the appended claims.

In the drawings, illustrating some of many possible embodiments of the mechanical features of this invention:

Figure 1 is a schematic vertical sectional view of a simple embodiment;

Figure 2 is a schematic vertical sectional view of an embodiment provided with a number of drawing-in openings;

Figure 3 is a schematic vertical sectional view of one .of the most preferred embodiments;

Figure 4 is a schematic lateral sectional view taken on the line 4-4 of Figure 3; h I

Figure 5 is a sectional view on an enlarged scale show-. ing a trap for the return of oil; and I Figure 6 is a schematic vertical axial sectional view. of a still another embodiment.

Similar numerals refer to similar parts throughout the several views.

Referring now to Figure 1, there are a boiler 11 and-a cylindrical pump body 41. The boiler 11 ishmade, of

. glass and provided with a neck 13. Thebottom 15. of the boiler 11 is inflated slightly. An electric heating unit 17 is provided inside the bottom 15 in a position as low as possible. The'electric heating unit 17 is adaptedto be energized suitably.

, The neck 13 of the boiler 11 isan integral part witha barrel or the wall 45 of the cylindrical body 41 of the pump, which extends vertically upwards. The body 41 is provided with an intake line 51 which inclines. upwards outwardly. 'Inside and concentrically with the body 41, there is an inner assembly comprising a guiding element 61-, an invertedly frustro-conical nozzle 71, a. spacing collar 93, a frustro-conical diffusing element 127, and'an inverted cup 1=29. 'Theinner assembly is made ofmetal sheets and interconnected by some fins (not shown) an ranged vertically and supported by the annular bottomr49 of the body 4 1. v i

The bottom of the guiding elementfil isadapted to-en gage with the neck 13 of the boiler 11 leaving a peripheral narrow clearance for the .return of oil. Therefore, when. condensed oil-fills up the clearance, no oil vapor.is;.per mitted to pass through it. The nozzle7lis attachedlto the top of'the guiding element 61. Therefore, .the. oil vapor is, permitted to pass through the single nozzle-throat 69 only. Thespacing collar 93 is arranged closelyl'above the top 73 of the noz'zle 71 which is larger than the bottom" of the collar93 in diameter so as toform an annularorifice 91 therebetween. The inner end of the intakelinefSl,- is positioned generally below the lev'el of the .top 73aof the nozzle 71. 'The diffusing. element 127. is. arranged closely above the top of the collar 93 whichi'issmaller than the bottom of-the diifusing element 127 so. as .to forth.

an annular opening125therebetween. Around the top portion of the diifusing element 1 27, there is theinver-ted cup 1 29 which divides the inside of the body-41.into two chambers, a high vacuum chamber 141 and a low vacuum 7 chamber 149. The periphery of the invertercup 129. en-

gages withthe wall"45 of the body 41 leavingsome clearance therebetween so as to pass the condensed .Ioil

" in'the'nozz'le'71. The. peripheral portion of the. oilwapor strear'ndhusforme'd is projected from thean nular.

level ofthe'intake line 51,while t.he-central portionlof through the spacing collar93 into the diffusing elemept 1 27. peripheral portion of the oil vapor stream is H ejected fromthe annular orifice 91 and forms an'invertedly frustro-conical partition of the oil vapor which divides the high vacuum chamber,141 into two regions,

the high vacuum region 143-and the low-vacuum region I 145; Thus the high-vacuumfregion 143 is communicated with the intake line'51. Gas molecules in the high vacuum region' 143 diffuse into the 'oil vapor partition and are carried thereby into the low vacuum region-145.

The central portion of the oil vapor streampassing through the spacingcollar93 and then the difiusing element127 aspirates gas molecules. in the low vacuum region 145 through the annular opening 125. The gascarrying oil vapor stream is released from the-top of the difiusing element 127 into the low vacuum chamber 149 where the oil vapor is condensed into a liquid state, while the gas is exhausted out of the low vacuum chamber 149 through the exhaust line 53by means of a mechanical pump (not shown). The oil condensed at the low vacuum chamber 149 is collected on the wall 45 of the body 41 and the periphery of the inverted cup 129, returns back into the high vacuum chamber 141 through the clearance prepared along with the periphery of the inverted cup 129, flows down along the wall 45 of the body 41, and returns back into the boiler 11 through the clearance aroundthe bottom of the 'guiding eleme'ntfil. Referring now to Figure 2 showing a modified em; bodiment, there are two frustro-conical drawing-in collars 77 and 81 and a diffusing collar 89 between the nozzle 71 and the spacing collar 93 ofthe foregoing"embodiment. There are three annular drawing-in openings 75, 79, and 87 between the top 73 of the nozzle 71 and the lower frustro-conical drawing-in collars 77, between the frustro-conical drawing-in collars 77 and .81, and between the upper one 81 thereof andlthe difiusing collar 89. The annular'orifice 91 is provided-between the diffusing collar 89 and the spacing collar 93, the top'of the diffusing collar 9 being larger than the bottom of the spacing collar 93 in diameter.

By virtue of the three drawing-in openings 75, 79,

and 87, gas molecules within the high vacuum region 143 together with the bottom electrical heating unit 17 by some suitable means; Preferably, the electrical heating units 17, 35 and 37 may becontrolled individually.

Inside the body 41 having the wall 45, the intake line 51 and the exhaust line 53, as in the foregoing embodiments, a more complicated assembly is contained. The assembly includes an upper inverted cup 129 and a lower inverted cup 105,015 which the ,former divides a chamtl her 149 positioned in the uppermost portion from a chamber 147 positioned in the intermediate portion andthe latter divides the chamber 147 from a chamber 141 positioned in the lowermost portion of the body 41.

The guiding element 61 has an annularly inflated skirt 63 at the lowermost end of the element 61. :The skirt 63 is provided with a number of vertical grooves 65 whereby the skirt 63 is kept in close contact with the inside of the neck 13 of the boiler '11 so that condensed oil is allowed to passthe clearance when theoil stays there to an extent. An umbrella 67 is provided around. an upper portion of the nozzle 71, resting on the 'shoul-' der of the body 41 so as to support the whole assem bly thereon associating with three vertical fins 155. Be-I tween the periphery of the umbrella 67 and the shoulder of the body 41, a clearance is provided so as towpas s;

' entrained with gas through thefseries of four drawing-in,

the oil vapor stream which carries less gas molecules passes.

upwards vertically through the spacing collar 93. Furthermore, the oil vapor stream jetted from the annular orifice 91 aspirates gas molecules from the high vacuum region 143 into the low vacuum region 145 directly through an annular orifice provided between the wall 41of the body 45 and the outer periphery of the difiusing'collar 89. Within the low vacuum region 145 of the high vacuum chamber 141 the. gas-carrying oil vapor is condensed by being cooled at the wall 45 of the body 41 separating the gas molecules which will'be drawn again through the drawing-in opening 125 by the central portion of the oil vapor stream not yet diifused with gas molecules einough.

Referring now to Figures Sand 4, one of the most preferred embodiments of this invention willbe explained.

In this embodiment a special boiler.11 having a three bulged side is used. The side of the boiler 11 comprises three annular bulges 21, 23, and 25 and two annular grooves 27 and 29 between the two of bulges, respectively, and is surrounded by a sheet 31 of a heat-coning material outside the heat-conductive sheet 31. Outside the insulating sheet 33, at the sametirne in the grooves 27 and 29, side electrical heating units 35 and 37 are arranged, respectively, which can be energized openings 75, 79, 83, and 87 is emittedfrom the annular first orifice 91 provided between the difiusing .collar 89'. and the spacing collar 93 and draws the gas molecules in the-high va'cuum region 143 by the invertedly frustro-conical partition of the entrained oil vapor up to the,

wall 45 of the body 41 also through an annular orifice, 7 provided between the wall 41 of the body 45 and the ,outer periphery of the diffusing collar 89.. And thus the partition fclivides the high vacuum chamber 14-1 intothe high vacuum region 143 and the low vacuum region 145,: as in the foregoing embodiments. a A

The lower inverted cup .105 is supported by a second: diffusing collar 103 which rests on the drawing-in:col lar 97, an annular drawing-inopening 99 being provided therebetween. Gas released from the entrained oilvaporpartition within the low vacuum region 145 is drawn through the annular openings 95 and 99 by the rather fresh, oil vapor stream. positioned at the near center of the noz; zle 71 and passing nearer the centers of the collars. Then the peripheral portion under considerationof the oil'vapor,

of the second diffusing collar 103 through which gas mole-a cules are aspirated from the region 145 into the inter-- mediate chamber 147 by the oil vapor stream jetted from: the annular orifice 117. t

Theentrained oil vapor released into the intermediate. chamber 147 is condensedby the cold wall 45 of the body 41 and returned to the high vacuum chamber141 along the wall 45 through a trap provided alongthe periphery of the lower inverted cup 105. A clearance isakept between the wall 45 of the body 41 and the periphery ofthe, lower inverted cup 105 and an annular flange 107 iSeX' tended downwards from the periphery. A trapring 109 1 having an inflatedskirt 111 is suspendedfrom the periph-..-

ery of the lowerinverted cup 105. Thus a traptor gas is,"

V formed-as shown in Figure 5. I-'he inflated skirt ll l is'a'rranged in close contact with the wall 45 by means ofa numberof vertical grooves 113.

u Gas released from the oil 'vaporwithi-n the intermediate chamber 147 is drawn again by a still more central portion of the oil vapor streampassing through thespacing collar 119 and drawing-in collars 123 and 127. F or the draw: ing-in of gas the annular drawing-in openings 121 and 125 are provided between these collars, respectively. Around the top of the uppermost drawing-in collar 127 an upper inverted cup 173 is arranged and constructed with another trap ring131 siinilarly'to the lower inverted cup105. Thus the upper inverted cup 129 is provided with a flange 137 and the trap ring 131 is provided with an inflated skirt 133 having a number of vertical grooves 135. Another outer concentric annular orifice 153; corresponding to the outerccncentricannular' orifice 151 is providedbetween the inner periphery of the upper inverted cup 129 and the top of the uppermost drawing-in collar 127 whereby gas within the intermediate chamber 147 is drawn into the low vacuumchamber 149.

It will be seen that the most peripheral 'portien f the oil vapor stream passing upwards through the. nozzle 71 acts at first to draw in gas molecules and is thencondense'd releasing the gas which is drawn by the intermediately peripheral portion of the oil vapor stream and then released by the condensation of the second-named portion of the oil vapor stream, and at last the released gas is drawn in by the most central portion of the oilvapor stream and carried thereby into the low vacuum chamber 149.

The uppermost member of the inside assembly is a transparent funnel 139 made of, for example, glass and restedon the top of the upper inverted cup 129 concentrically. This is an only partmade of glass within the construction of the inner assembly. The glass funnel 139 functionates a gauge indicating the degree of vacuum. That is, in the early period of the evacuating operation, a condensed oil ring may be found inside the glass wall of the funnel 139. The ring asceiids gradually along the wall as the vacuum impmvesand at last disappears from thetop of the wall of the glass funnel'13'9'. Subsequently, another ring of the condensed oil may be found inside the glass wall 45 of the low vacuum chamber 149 which ring also ascends as the proee'sser the evacuatin 6peratio'n. At last such a nngtmy not be found anywhere. In the light of experiences, those skilled in the art' may estimate the degree of vacuum by the position of the The oil condensed in the low vacuum chamber 149 is collected along the clearance provided between the wall 45 of the body 41 and the periphery of t-he upper inverted cup 129 and returned on the wall 450 15 the inter mediate chamber 147 through the trap provided'a lon'g said clearance. The condensed oil flowing down along the wall 45 of the intermediate ehamber'14'7 is similarly collected along the clearance provided between the wall 45 and the periphery of the lower" inverted cup 105 together with the oil condensed within the intermediate chamber 147 and returned on the wall 45 of the high vacuum chamber 141. The condensed oil flowing further along the wall 45 is collected along'the clearance provided around'the skirt 63 of the guiding element 61 and returned into the boiler 11. The returned oil flows "along the specially shaped side wall of the boiler l'l-into the lot of the oil accumulated on the bottom 15. Now by virtue of the special shape of the side wall of the boiler lland action of the side electrical heating units and 37 explained hereinbefore, the down-flowing oil is heated so as to be re-vaporized extremelysmo'othly resulting in that there is no fear of oil bumping. On the other hand, the upper part of the wall of the body 41 maybe cooled externally, for example, by means of arranging a coil of water pipe around the part through which cold water may be passed.

: a conventional type.

.:::By virtueof the arrangementof collars with openings provided therebetween, the oil condensed inside'the collars' from the flowing oil vapor which passes through the collars is expelled through the openings out of the collars so as to keep the inside from obstruction caused by the condensed oil against the passage of the oilvapor stream.

"While up-jet oil diifusion pumps only have been 'disclosed hereinbefore as embodiments of this invention, it should be understood that this invention is not limited to such particular arrangements disclosed and the principle of this invention may be applied for other arrange ments of diffusion pumps. To this end still another embodirnent is illustrated in Figure 6 schematically wherein a pump is arranged laterally. Parts thereof are similar to those described with respect to the embodiment shown in Figure 1. It is considered that it is not necessary to explain the arrangements and functions of this pump particularly.

By virtue "of this invention, a vacuum of 10- mm. Hg could 'be' achieved in a certain case within a period of 20 secondswhileit is necessary to take a period of a matter of 70 minutes in order to achieve the same degree of vacuum by means of a'most effective pumping system of Furthermore, an auxiliary mechanicalipumpof less capacity will suflice by this invention than the conventional type of the diffusion pump.

'Many modifications within the scope of the invention described above will be apparent to those skilled in the art 'without a departure from the inventive concept. "I

do not'wish to be limited to the forms herein particularly shown and specifically "described, but rather intend that' the invention shall include all reasonable equivalents thereof.

I claim:

1. An oil difiusion pump comprising a boiler, a cylindrical body disposed above and communicating'with said boiler, said body being divided into a high vacuum chamber and a low vacuum chamber and having an inner assembly, an exhaust line communicating with said low vacuum chamber, and a descending intake line; said inner assembly being arranged concentrically with said body and comprising a tapered nozzle through which a stream ofoil vapor is madeto flow, a heating elementl'oca'ted in heating relation to said boiler adjacent the narrow end of said tapered nozzle, said intake line entering said cylindri cal body adjacent said tapered nozzle, a frustro conical spacing collar having its Wide end adjacent the wide end of said nozzle, the wide end of said spacing collar being of less diameter than the wide end of said nozzleand spaced therefrom, a frusto-conical diffusing element having its wide end adjacent but spaced from the small end of said spacing collar, said last mentioned wide end being of greater diameter than said small end of said spacing" collar, said tapered nozzle, said frustro-conical spacing collar and said frustro-conical dilfusing element being dis posed in said high vacuum chamber, said frustroconical diffusing element having its narrow'end terminating in said low vacuum chamber, the peripheral portion ofsaid stream drawing gas molecules within said high vacuum chamber, and said drawn gas molecules being carried by the central portion of said stream into said low'vacuum chamber.

2. An oil diifusion puinp comprising'a boilerfacylindrical body arranged vertically on and communicating with said boiler, said'body being divided into a high vac uum chamber and a low vacuum chamber positioned above the former, and having a vertically arranged inner I assembly and a descending intake line, an exhaust line communicating with said low vacuum chamber, said inner assembly being arranged concentrically with said body and comprising a tapered nozzle through which a stream of oil vapor is made to flow, a heating element located in heating relation to said boiler'and'disposed adjacent the narrow end of said tapered nozzle, said intake line nozzle-, a frustro-conical spacing collar having its wide end adjacent'the wide end of said nozzle, the wide end of said spacing collar being of less diameter than the'wide end of said nozzleand spaced therefrom, and a frustroconical diffusing element having its wide end adjacent but spaced from'the small end of said spacing collar, said Wide end of said frustro-conical diffusing element being of greater diameter than said small end of said spacing collar, said tapered nozzle, said frustro-conical spacing collar and said frustro-conical diffusing element being disposed in said high vacuum chamber, and said frustro-conical diffusing element having its narrow end terminating in said low vacuum chamber, the peripheral portion of said stream drawing gas molecules within said high vacuum chambenand said drawn 'gas molecules being. carried by the central portion of said stream into said low vacuumchamber.

3. An oil difiusion pump comprising a boiler, a cylindrical body divided into a high vacuum chamber and a low vacuum chamber, said boiler having a neck and a heating element associated therewith to evaporate oil therein, said body being arranged vertically on and communicating with said boiler and including an inner assembly, a descending intake line, and an exhaust "line communicating with said low. vacuum chamber, said ing a peripheral clearancefor returning oil, said nozzle being supported on said guiding element so as toiritroduce the whole quantity of oil vapor only through said nozzle, said'spac'ing collar being arranged above the top of said nozzle and the bottom of said spacing collar being smaller in diameter than said top of said nozzle, saiddiffusing element being arranged above said spacing collar and the bottom of said ,difiusing elementbeinglarger than the top of said spacing collar, said inverted cup being arranged around the top portion of said difiusingelement and across the inside of said body and leaving a pcripheral clearance for returning oil, said intake line being incommunication with a high'vacuum region of said highzvacuum chamber, said region being defined by the wallet said body, said guiding element, said nozzle and an oil partition film formed by the peripheral portion of the oil vapor stream jetted from an annular orifice formed between the top of said, nozzle and the bottom of "said spacing collar,gas within said high vacuum regionrand said intake line being carried by the jetted partition into a low, vacuum region separated from said high vacuum region by said oil partition film within said high vacuum chamber, the gas carried by said partition into said low vacuum region being drawn through an annular openingprovided between the top of said spacing'collar and the bottom of said diffusing element by the central portion of said oil vapor stream passing through the spacing collar and the difiusing element intoa'low vacuum chamber arranged above said inverted cup, the oil being condensed out of-the gas-carrying vapor within said low vacuum chamber and returned to the boiler through saidclearthe lo'wfvacuum chamber, through which thegW'hOIG;

introduced into said low quantity of oil vapor stream is vacuum chamber.

5. An oil difiusion pumpcomprising a boiler, a cylindrical body divided into a high vacuum chamber and a low vacuum chamber, said boiler having a neck and a heatingvelement associated therewith to evaporate oil therein, said body being arranged; on and conununicating claimed in claim sfa with said boiler and comprising-a generally cylindrical wall, an inner assembly, a descending intake line and an exhaust -line.communicating with said low vacuum chamber, said inner assembly havingmembers arranged I concentrically with said body and comprising a guiding element, an inverted frustro-conical nozzle, a first frustro: conical drawing-in element, a first difiusing element, a,

' first spacing collar, a second frustro-conical drawing-in element, a second difiusing elementQa second spacing? collar, a third frustro-conical drawing-in element, and

a transparent funnel arranged vertically inthe order' stated, the bottom of each of said drawing-in elements and difiusing elements being larger in diameter than the top of a member positioned directly below so as to provide an annular opening 'therebetween, the top of each of said difiusing elements being largerthan'the bot-j tom of a member positioned directly above in diameter so as to provide an annular orifice therebetween, said guiding element being adapted to engage with said neck of the boiler and leaving a peripheral clearance for returning oil, said nozzle being supported on said guiding element so as to introduce the whole quantity of the oil'vapor stream only throughsaid nozzle, inverted cups being supported around the tops of said second diffusing 7 element andtsaid third drawing-in, element and adapted to divide the inside space of said body into a highvacuum t chamber, an intermediate vacuum chamber, and a lowfl vacuum chamber, clearances for returningthe oil being I left between the peripheries of said inverted cups and said wall, and thetop of 'said first diffusing element being spacing collar, dividing said high vacuum chamber into a high vacuum region communicating with said intake line and a low vacuum region, whereby gas molecules within said high vacuum region are drawn in through openingsprovided under said first drawing-in element andsaid firsttditfusing element by the peripheral porti tion of the oil vapor stream emitted from said nozzle, and drawn in by the oil vapor film, the major portion of the gas molecules thus drawn in being released into said .low vacuum region and again drawn in through openings 1 provided under said second drawing-in elements and said second diffusing element by the peripheral portion in question ofthe oil vapor stream passing therethrough, and a major portion of the gas molecules thus drawn in i being released into said intermediate vacuum chamber,

again being drawn in through openings provided under said third drawing-in element by the peripheral portion of the oil vapor stream passing therethrough and released through said: transparent funnel into said low vacuum a chamber whence the gas molecules are exhausted out of the pump through an exhaust line and the oil vapor boiler having an annular multiple-bulged side, an an- 1 nular groove being provided between any proximate two of saidbulges, a sheet of insulating material andva sheet of heat conductive material, said side beingvsurrounded by said sheet of a beat-conductive material which is r --furtherI surroundedby saidsheet of electric insulating material, and an electrical heating unit being arranged w in each of said grooves outside of said insulating material, said heating element being arranged in said boiler, said heating units and said heating element being sele'c- "tively energizable singly and in combination;

References Cited in the file of thispatent "V UNITED STATES PATENTS Leblanc July 9, 1912 Q 

